# -*- coding: utf-8 -*-

# Define here the models for your spider middleware
#
# See documentation in:
# https://doc.scrapy.org/en/latest/topics/spider-middleware.html
import random
from scrapy import signals
from ArticleSpider.settings import USER_AGENTS
#from tools.crawl_xici_ip import GetIp
class ArticlespiderSpiderMiddleware(object):
    # Not all methods need to be defined. If a method is not defined,
    # scrapy acts as if the spider middleware does not modify the
    # passed objects.

    @classmethod
    def from_crawler(cls, crawler):
        # This method is used by Scrapy to create your spiders.
        s = cls()
        crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
        return s

    def process_spider_input(self, response, spider):
        # Called for each response that goes through the spider
        # middleware and into the spider.

        # Should return None or raise an exception.
        return None

    def process_spider_output(self, response, result, spider):
        # Called with the results returned from the Spider, after
        # it has processed the response.

        # Must return an iterable of Request, dict or Item objects.
        for i in result:
            yield i

    def process_spider_exception(self, response, exception, spider):
        # Called when a spider or process_spider_input() method
        # (from other spider middleware) raises an exception.

        # Should return either None or an iterable of Response, dict
        # or Item objects.
        pass

    def process_start_requests(self, start_requests, spider):
        # Called with the start requests of the spider, and works
        # similarly to the process_spider_output() method, except
        # that it doesn’t have a response associated.

        # Must return only requests (not items).
        for r in start_requests:
            yield r

    def spider_opened(self, spider):
        spider.logger.info('Spider opened: %s' % spider.name)


class ArticlespiderDownloaderMiddleware(object):
    # Not all methods need to be defined. If a method is not defined,
    # scrapy acts as if the downloader middleware does not modify the
    # passed objects.

    @classmethod
    def from_crawler(cls, crawler):
        # This method is used by Scrapy to create your spiders.
        s = cls()
        crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
        return s

    def process_request(self, request, spider):
        # Called for each request that goes through the downloader
        # middleware.

        # Must either:
        # - return None: continue processing this request
        # - or return a Response object
        # - or return a Request object
        # - or raise IgnoreRequest: process_exception() methods of
        #   installed downloader middleware will be called
        return None

    def process_response(self, request, response, spider):
        # Called with the response returned from the downloader.

        # Must either;
        # - return a Response object
        # - return a Request object
        # - or raise IgnoreRequest
        return response

    def process_exception(self, request, exception, spider):
        # Called when a download handler or a process_request()
        # (from other downloader middleware) raises an exception.

        # Must either:
        # - return None: continue processing this exception
        # - return a Response object: stops process_exception() chain
        # - return a Request object: stops process_exception() chain
        pass

    def spider_opened(self, spider):
        spider.logger.info('Spider opened: %s' % spider.name)

class RandomUserAgentMiddlware(object):
    # def __init__(self,crawler):
    # http: // python.jobbole.com / 86787 /
    #     #super(RandomUserAgentMiddlware,self).__init__() python2写法
    #     super().__init__() #python3写法
    # @classmethod
    # def from_crawler(cls,crawler):
    #     return cls(crawler)
    ##############################上面被注释的代码目前看没有任何作用###################################


    # 定义一个专门用于处理请求的函数:两个参数，第一个参数就是要处理的请求对象，第二个参数是爬虫程序
    # 该函数必须返回一个数据-None/request，如果返回的是None,表示处理完成，交给后续的中间件继续操作
    # 如果返回的是request,此时返回的request会被重新交给引擎添加到请求队列中，重新发起
    def process_request(self, request, spider):
        print('----QAQ-----')
        # 随机获取一个user-Agent
        useragent = random.choice(USER_AGENTS)
        # 给request请求头中添加user-agent配置
        request.headers.setdefault('User-agent', useragent)
        return None

# class RandomProxyMiddleware(object):
#     #动态设置ip代理
#     def process_request(self,request,spider):
#         get_ip=GetIp()
#         request.meta["proxy"]=get_ip.get_random_ip()
